Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry
Characterization of supercooled liquid Ge2Sb2Te5 and its crystallization by ultrafast-heating calorimetry
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DOI：
10.1038/nmat3275
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发表时间：
2012-04-01
期刊：
影响因子：
41.2
通讯作者：
Smith, C. E.
中科院分区：
文献类型：
--
作者：
Orava, J.;Greer, A. L.;Smith, C. E.
差示扫描量热法（DSC）被广泛用于研究非晶固体的稳定性，表征接近玻璃化转变温度T-g的结晶动力学。我们将超快DSC应用于相变材料Ge2Sb2Te5 (GST)，并表明如果加热速率范围扩展到10(4)K s（-1）以上，分析可以覆盖更宽的温度范围，直到晶体生长速率接近其最大值的点。可以描述的增长率比传统的DSC高大约四个数量级，达到与将商品及服务税应用为数据存储介质有关的值。晶体生长的动力学系数具有强烈的非阿伦尼乌斯温度依赖性，表明过冷液体GST具有高脆性。在Tg附近，有证据表明晶体生长动力学与粘性流动解耦，与氧化物和有机系统研究中提出的脆弱液体的行为相匹配。
Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature T-g. We apply ultrafast DSC to the phase-change material Ge2Sb2Te5 (GST) and show that if the range of heating rates is extended to more than 10(4) K s(-1), the analysis can cover a wider temperature range, up to the point where the crystal growth rate approaches its maximum. The growth rates that can be characterized are some four orders of magnitude higher than in conventional DSC, reaching values relevant for the application of GST as a data-storage medium. The kinetic coefficient for crystal growth has a strongly non-Arrhenius temperature dependence, revealing that supercooled liquid GST has a high fragility. Near Tg there is evidence for decoupling of the crystal-growth kinetics from viscous flow, matching the behaviour for a fragile liquid suggested by studies on oxide and organic systems.